On the weekend before the Fourth of July 1966, the U.S. Office of Education quietly released a 737-page report that summarized one of the most comprehensive studies of American education ever conducted. Encompassing some 3,000 schools, nearly 600,000 students, and thousands of teachers, and produced by a team led by Johns Hopkins University sociologist James S. Coleman, "Equality of Educational Opportunity" was met with a palpable silence. To the dismay of federal officials, the Coleman Report had concluded that "schools are remarkably similar in the effect they have on the achievement of their pupils when the socio-economic background of the students is taken into account." Or, as one sociologist supposedly put it to the scholar-politician Daniel Patrick Moynihan, "Have you heard what Coleman is finding? It's all family." So what exactly had Coleman uncovered? Differences among schools in their facilities and staffing "are so little related to achievement levels of students that, with few exceptions, their effect fails to appear even in a survey of this magnitude," the authors concluded. The associations between home life and school performance that Coleman documented may actually be driven by disparities in school or neighborhood quality rather than family influences. In the elusive quest to uncover the determinants of students' academic success, therefore, it is important to rely on experimental or quasi-experimental research that identifies effects of family background that operate separately and apart from any school effects. In this article, the author looks at four family variables that may influence student achievement: family education, family income, parents' criminal activity, and family structure. She then considers the ways in which schools can off-set the effects of these factors. [This article is part of a new "Education Next" series commemorating the 50th anniversary of James S. Coleman's groundbreaking report, "Equality of Educational Opportunity." The full series appears in the Spring 2016 issue of "Education Next."]